Improved photo sensing behavior of the terbium doped In2S3 thin films synthesized by spray pyrolysis technique

Abstract

In the present work, undoped In2S3 and varying concentrations of Tb (1, 2, 3, 4 & 5 wt%) doped In2S3 thin films were synthesized using the economical and nebulizer spray pyrolysis technique for studying their photosensing characteristics at room temperature. X-ray diffractometer (XRD) studies showed the diffraction pattern of the thin films exhibits a cubic- β phase of In2S3 and the highest crystallite size of 61 nm was observed for the In2S3: Tb (2wt%) thin film. The morphological & elemental analysis showed that all the synthesized thin films exhibit homogeneous non-uniform crystal morphology with the existence of S, In, Tb compounds with their distinct composition. From Ultraviolet-Visible(UV–vis) studies, all the prepared thin films exhibit maximum absorption in the UV region with a minimum bandgap of 2.85 eV for the In2S3:Tb (2wt%) thin film. Also, the Photoluminescence (PL) spectra showed that the In2S3:Tb (2wt%) thin film possesses two large intense emission peaks around ∼470 nm (Yellow) and 530 nm (green). Finally, the photo sensing studies showed that the fabricated In2S3:Tb (2wt%) thin film photodetector showed better photocurrent, Responsivity (R), Detectivity (D*), External Quantum Efficiency (EQE), Response/Recovery time values of ∼12.5 μA, 0.296 AW−1, 7.75 × 1010 Jones, 60%, 2.9/3.6 s, respectively indicating the device better suitable for commercial photodetector application.